102×45
=100×45+2×45
=4500+90
=4590；
8.76-5.29-2.71+1.24
=8.76+1.24-（5.29+2.71）
=10-8
=2；
3.31-18.3÷7×0.5
= 3.31-18
3
10 ×
1
7 ×
1
2
= 3.31-
183
10 ×
1
7 ×
1
2
=3
31
100 -
183
140
=
331
100 -
183
140
=
2317
700 -
915
700
=
1402
700
= 2
1
350 ；
1-（
1
5 +
1
3 ）×
15
8
=1 -
1
5 ×
15
8 -
1
3 ×
15
8
= 1-
3
8 -
5
8
=0；
24×
51
43 +51×
19
43
=24×
51
43 +19×
51
43
=（24+19）×
51
43
=43×
51
43
=51；
9
14 ÷（
5
6 -
3
4 ）×
7
24
=
9
14 ÷
1
12 ×
7
24
=
9
14 ×12×
7
24
=
9
4 ．